Tim has an odd issue with some bridged interfaces and overlapping addressing  
so I was telling him to subnet and renumber hence my ‘cheat sheet’, 
unfortunately I’ve praying to the porcelain god and I wasn’t able to follow up 
with him on his next set of questions which lead him to ask here.

 

--

For me and how I’ve been helping him, every site/pop has a unique site ID and a 
/24 of  private ip’s assigned to that site based upon the site ID for 
management of devices at that site IE 10.100.siteid.0/24 with a loopback IP of 
a.a.a.siteid/32 for the router on site.

 

For wireless sites, radio links are on /29’s most everything else on /30’s. I 
mentally set aside the first /26 for backhauls links and the last /26 for 
‘local’ devices ie switches, ups’s etc. Everything in between is customer 
access devices – AP’s (generally numbered clockwise starting from north).

 

I started off doing /30’s on backhauls but found they are hard to keep track of 
– plus with ospf and a series of network rings how do you know the radio link 
is blown but the radio itself is still responding? (assuming you are not 
alarming on snmp stats or have a radio where the eth port follows the wireless 
link). *I alarm on other factors rather than the radio just responds to pings 
so it’s a moot issue now, but early on it was pain.

 

Using a /29  for backhaul links and the ip scheme that Tim shared I can quickly 
tell just by the IP on the router whether it’s attached to a backhaul, if that 
backhaul is terminating or originating on that site and if its terminating what 
is the originating site. 

So if I’m logged into site 55 and I see the IP address of 10.100.17.28/29 
assigned to eth1 I know it’s a backhaul link and that the other end is site 17. 

If the IP is 10.100.55.10, I know the router at the other end is 10.100.55.12 
etc.

 

YMMV, everyone has a different scheme that works for them. What is more 
important is standardizing and sticking with it. My site scheme is muscle 
memory anymore so I can rebuild a site with minimal documentation – usually the 
labels on cables, poe’s etc is enough to get 90% of the site rebuilt with the 
rest coming from site documentation. Really helps for those bleary eyed alarms 
at 3am after a site has been smoked.

 

 

 

From: Af [mailto:[email protected]] On Behalf Of Hass, Douglas A.
Sent: Wednesday, August 26, 2015 1:19 PM
To: [email protected]
Subject: Re: [AFMUG] Issues with doing /29 inside of routerboard

 

Exactly.  The site ID piece gets confusing if you try to number by backhaul.  I 
think it makes more sense to assign subnets by physical location.

 

Tower site 1:  10.100.1.x/24

Tower site 20: 10.100.20.x/24

Tower site 30: 10.100.30.x/24

 

And so forth.  This still lets you do something consistent like this:

 

Tower site 1—Tower site 20 backhaul:

 

10.100.1.21/24 – local radio

10.100.1.22/24 – local router interface

10.100.20.1/24 – remote radio

10.100.20.2/24 – remote router interface

 

Tower 1—Tower site 30 backhaul

 

10.100.1.31/24 – local radio

10.100.1.32/24 – local router interface

10.100.30.1/24 – remote radio

10.100.30.2/24 – remote router interface

 

The biggest problem I had with using /30s was that unless I set up DNS, I lost 
track of what /30 belonged to what site once I had more than a handful of 
backhauls.  Numbering this way, without DNS, all I have to know is what the 
site ID is.

 

Doug

 

From: Af [ <mailto:[email protected]> mailto:[email protected]] On Behalf 
Of That One Guy /sarcasm
Sent: Wednesday, August 26, 2015 1:03 PM
To:  <mailto:[email protected]> [email protected]
Subject: Re: [AFMUG] Issues with doing /29 inside of routerboard

 

Site 33:

 

 <http://10.100.33.0/24> 10.100.33.0/24  (.1 local radio, .2 local router, .101 
remote radio, .102 remote router)

 

Site 34:

 

 <http://10.100.34.0/24> 10.100.34.0/24  (.1 local radio, .2 local router, .101 
remote radio, .102 remote router)

 

 

If these are talking to one another with this scheme, the routers may be able 
to have multiple IPs but very few radios allow multiple IPs on the device

 

Site 33 local radio is 10.100.33.1 to site 33, but that same radio to site 34 
would be 10.100.34.101

 

On Wed, Aug 26, 2015 at 12:59 PM, Hass, Douglas A. <[email protected] 
<mailto:[email protected]> > wrote:

 

Back to your original question, though—you would have to renumber if you’re 
already using a /24 on an interface and now want to carve that particular /24 
up in /29s.

 

But if you’re using private IP space, why limit yourself to /29s everywhere?  
Particularly if each site would have a site number, you could easily do:

 

Site 33:

 

 <http://10.100.33.0/24> 10.100.33.0/24  (.1 local radio, .2 local router, .101 
remote radio, .102 remote router)

 

Site 34:

 

 <http://10.100.34.0/24> 10.100.34.0/24  (.1 local radio, .2 local router, .101 
remote radio, .102 remote router)

 

And so on…

 

Leave yourself plenty of room and route bigger subnets.  The site numbering 
idea might end up a little confusing, though, since “Site 33” is really TWO 
physical sites, and “Site 34” in my example above is TWO physical sites, one of 
which you’ve already called part of Site 33.

 

Doug

 

 

From: Af [mailto: <mailto:[email protected]> [email protected]] On Behalf 
Of Tim Reichhart
Sent: Wednesday, August 26, 2015 12:32 PM
To:  <mailto:[email protected]> [email protected]


Subject: Re: [AFMUG] Issues with doing /29 inside of routerboard

 

Mike
basically rob haas was helping me out on this he sent me an little cheat sheet 
like this:

 

a /29 – 255.255.255.248 is what I use on the backhauls

Each Site is assign a site number – say 33

Every site is assigned a /24 for management with my IP scheme of 10.100.site.X

The first backhauls would fall into 10.100.33.0/29 <http://10.100.33.0/29>  so:

10.100.33.1 – Local radio

10.100.33.2 – Local Router

10.100.33.3 – Remote Radio

10.100.33.4 – Remote Router

 

The next backhaul would be out of 10.100.33.8/29 <http://10.100.33.8/29>  so:

10.100.33.9 – Local Radio

10.100.33.10 – Local Router

10.100.33.11 – Remote Radio

10.100.33.12 – Remote Router

 

basically I want break down the ip's down for backhauls.

 

Tim


  _____  


-----Original Message-----
From: "Mike Hammett" < <mailto:[email protected]> [email protected]>
To:  <mailto:[email protected]> [email protected]
Date: 08/26/15 01:23 PM
Subject: Re: [AFMUG] Issues with doing /29 inside of routerboard

Can you tell us the bigger picture of what's going on so we can help better?



-----
Mike Hammett
Intelligent Computing Solutions
 <http://www.ics-il.com> http://www.ics-il.com
 

 


  _____  


 From: "Tim Reichhart" < <mailto:[email protected]> 
[email protected]>
To:  <mailto:[email protected]> [email protected]
Sent: Wednesday, August 26, 2015 12:09:01 PM
Subject: Re: [AFMUG] Issues with doing /29 inside of routerboard


I was told to take that /24 and break it down to /29. But I didn't see an way 
to make work without readdressing whole subnet.

Tim

-----Original Message-----
Subject: Re: [AFMUG] Issues with doing /29 inside of routerboard
From: "Mike Hammett" < <mailto:[email protected]> [email protected]>
To:  <mailto:[email protected]> [email protected]
Date: 2015/08/26 18:59:54

I did not, no.




-----
Mike Hammett
Intelligent Computing Solutions
 <http://www.ics-il.com> http://www.ics-il.com
 

 From: "Josh Luthman" < <mailto:[email protected]> 
[email protected]>
To:  <mailto:[email protected]> [email protected]
Sent: Wednesday, August 26, 2015 11:58:27 AM
Subject: Re: [AFMUG] Issues with doing /29 inside of routerboard


Did you mean a /29 on eth1?
Josh Luthman
Office:  <tel:937-552-2340> 937-552-2340
Direct:  <tel:937-552-2343> 937-552-2343
1100 Wayne St
Suite 1337
Troy, OH 45373On Aug 26, 2015 12:53 PM, "Mike Hammett" < 
<mailto:[email protected]> [email protected]> wrote:

You can't have overlapping subnets.



-----
Mike Hammett
Intelligent Computing Solutions
 <http://www.ics-il.com> http://www.ics-il.com
 

 From: "Tim Reichhart" < <mailto:[email protected]> 
[email protected]>
To:  <mailto:[email protected]> [email protected]
Sent: Wednesday, August 26, 2015 11:52:43 AM
Subject: [AFMUG] Issues with doing /29 inside of routerboard

Hi guys
I am having bit of an issue getting /29 to work in routerboard. What I am 
looking to do is put 172.16.2.x/29 on ether2 but I already have  
<http://172.16.2.1/24on> 172.16.2.1/24on ether1. So I don't know what I am 
missing here.

 
 
 
 
 


 


 



Douglas A. Hass
Associate
312.786.6502 <tel:312.786.6502> 
[email protected] <mailto:[email protected]> 

Franczek Radelet P.C.

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Connect with me:


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